Doxapram hydrochloride is a short-acting, centrally-acting respiratory stimulant. It acts primarily on the peripheral carotid chemoreceptors and secondarily on the central respiratory centers in the medulla. In the Indian context, it is a critical drug used in hospital settings for the management of acute respiratory depression, particularly in post-anesthetic recovery and drug-induced CNS depression. Its use requires careful monitoring due to its narrow therapeutic index and potential for significant adverse effects.
Adult: IV administration only. For post-anesthetic depression: Initial single IV injection of 0.5-1 mg/kg (max 1.5 mg/kg), repeated every 5 minutes as needed, up to a total of 2 mg/kg. For drug-induced depression: A loading dose of 1-2 mg/kg IV, followed by a continuous IV infusion at 1-3 mg/minute, titrated to maintain adequate ventilation. Max total dose: 3 g/24h.
Note: For IV injection: Dilute with 5% Dextrose or Normal Saline. Administer slowly over at least 30 seconds to 1 minute. For IV infusion: Dilute 250 mg (12.5 mL of 20mg/mL solution) in 250 mL of 5% Dextrose or Normal Saline (resulting concentration: 1 mg/mL). Infuse using an infusion pump. Continuous monitoring of ECG, blood pressure, respiratory rate, and arterial blood gases is mandatory. Patient must be in a setting where intubation and mechanical ventilation are immediately available.
Doxapram stimulates respiration by a dual mechanism. Its primary action is on the peripheral carotid chemoreceptors, increasing their sensitivity to arterial pCO2 and hydrogen ion concentration. This leads to reflex stimulation of the medullary respiratory center. At higher doses, it has a direct stimulant effect on the medullary respiratory center, increasing the depth and rate of breathing. It also causes mild CNS stimulation, increasing alertness.
Pregnancy: Pregnancy Category B (US FDA). Animal studies have not shown teratogenicity, but adequate human studies are lacking. Use only if the potential benefit justifies the potential risk to the fetus. Can cross the placenta.
Driving: Patients should be advised that doxapram may cause dizziness, restlessness, and altered coordination. Driving or operating heavy machinery should be avoided until the effects have completely worn off, which is typically several hours after administration.
| Sympathomimetics (e.g., Adrenaline, Noradrenaline) | Additive pressor effects; risk of severe hypertension and arrhythmias. | Major |
| MAO Inhibitors (e.g., Phenelzine, Selegiline) | Exaggerated hypertensive crisis and hyperpyrexia. | Major |
| Volatile Anesthetic Agents (Halothane, Enflurane) | Increased risk of arrhythmias, especially with catecholamine release. | Major |
| Theophylline/Aminophylline | Additive CNS stimulant effects; increased risk of seizures. | Major |
| CNS Depressants (Opioids, Barbiturates, Benzodiazepines) | Doxapram may temporarily antagonize respiratory depression but does not reverse CNS depression. Risk of delayed CNS depression once doxapram wears off. | Moderate |